HP OpenVMS Systems Documentation

Displays information about the SAS expander connected to the SAS Controller.

Format

SHOW EXPANDER [exp_id]

Parameters

exp_id

Displays information about a specific SAS expander.

If an expander ID is not specified, the SAS utility displays all available SAS expanders that the SAS Controller finds.

Qualifiers

/FULL

Displays additional information about the expanders in the SAS domain.

Example

   SAS> SHOW EXPANDER 
 
Expander 1 
        Physical Port   : 0 
        SAS WWID        : 500508B3-00A1396F 
        Dev Handle      : 9 
        Num PHYs        : 13 
        SAS Level       : 1 
        Exp Flags       Device has configurable route table. 
        Prog Link Rate  Max 3.0Gbps  Min 1.5Gbps 
        HW Link Rate    Max 3.0Gbps  Min 1.5Gbps 
        PHY Info        Table Routing  3.0Gbps speed 
        Att Dev Info    SMP Target   LSI Device 
 
      

This example shows information about external SAS Expander 1, which is connected to the SAS Controller.

Displays SAS PHY information for all connections in the SAS Controller.

Format

SHOW PHY [phy_id]

Parameters

phy_id

Display information about a specific SAS PHY ID. (Use the SAS command SHOW DISK to display SAS PHY IDs.)

If a PHY ID is not specified, the utility displays all available PHYs on the SAS Controller.

Qualifiers

/ERROR

Displays SAS PHY error counters.

/FULL

Displays additional information about the PHYs.

Example

   SAS> SHOW PHY 0 
 
PHY 0 
        OwnerDev                : 1 
        SAS WWID                : 5000C500-003306B1 
        DevHandle               : 9 
        PhyIdentifier           : 0 
        Device Info             SSP Target   Direct Attached 
        Flag                    SGPIO DA Enclosure present. 
        PHY Info                3.0Gbps speed 
SAS> 
      

This example shows the SAS PHY connection for PHY 0.

Displays the IR volumes configured in the SAS Controller.

Format

SHOW UNIT [volume_id]

Parameters

volume_id

Displays information about a specific IR volume.

If a volume ID is not specified, the SAS utility displays all available IR volumes that the SAS Controller finds.

Qualifiers

/FULL

Displays additional information about IR volumes.

Example

   SAS> SHOW UNIT 
 
 IR Volume information: 
 
 -------------- 
 IR Volume 4 
 -------------- 
 Volume Type          : RAID 1 (LSI Logic Integrated Mirror) 
 Volume State         : Optimal 
 Size                 : 69495 MB / 142325760 blocks 
 
 IR Disk 1            Source Disk 
    Disk State        : Online 
    Slot ID           : 1 
    SAS WWID          : 5000C500-0134CB8D 
 
 IR Disk 0            Secondary Disk 
    Disk State        : Online 
    Slot ID           : 7 
    SAS WWID          : 5000C500-0134DBB5 
 
 IR Hot Spare         7 
    Hot Spare Status  : Active 
    Slot ID           : 6 
    SAS WWID          : 12210000-06000000 
 
      

This example displays volume information and all physical disks corresponding to the IR volume set.

Displays the version number of the SAS utility that you are currently using.

Format

SHOW VERSION

Example

   SAS> SHOW VERSION 
   SAS$UTIL Version 1.0 
   Build 05-May-2006 
      

This example shows that this version of the SAS utility is 1.0.

The SCA Control Program (SCACP) utility is designed to monitor and manage cluster communications. It is derived from the Systems Communications Architecture (SCA), which defines the communications mechanisms that allow nodes in an OpenVMS Cluster system to cooperate.

SCA does the following:

• Governs the sharing of data between resources at the nodes
• Binds together System Applications (SYSAPs) that run on different Integrity servers, Alpha, and VAX computers

Historically, LAN cluster port information has been available only in the System Dump Analyzer (SDA) utility and by using the Availability Manager management tool. The ability to start and stop PEdriver on a LAN device was provided by SYS$EXAMPLES:SYS$LAVC_START_BUS.EXE and SYS$LAVC_STOP_BUS.EXE. No way existed to prioritize use of LAN devices or individual channels.

SCACP provides an alternative method of collecting cluster management data and exercising management control over cluster communications. OpenVMS Version 7.3 introduced SCACP's ability to manage SCA use of LAN paths. Beginning with OpenVMS Version 7.3-1, you can use SCACP to manage all OpenVMS Cluster interconnects.

Starting with OpenVMS Version 8.4, OpenVMS is enhanced to use IP (Internet Protocol) for cluster communications. OpenVMS cluster over IP (also referred to as IP Cluster Interconnect) is the ability to use TCP/IP stack for cluster communications in addition to LAN. PEdriver which implements the cluster communication protocol uses UDP (User datagram protocol) for cluster communication.

21.1.1 Terminology Related to SCACP

Definitions of terms that are related to SCACP are in the following sections.

21.1.1.1 SCS Ports and Circuits

SCA communications mechanisms between nodes are defined in terms of System Communications Services (SCS) ports and circuits:

• An SCS port is any device that provides SCA communications services.
• An SCS circuit is an SCS port layer connection that provides a standardized set of services using a reliable port-to-port communication connection between OpenVMS Cluster nodes.

After a circuit is formed between two ports, communication using the SCS services can be established between SYSAPs in the nodes. In a cluster, each port maintains a circuit with every other remote port.

Circuits provide the SCS layer with the following standardized SCS services:

• Datagram delivery
• Message delivery
• Block data read and write operations

A virtual circuit (VC) is the interconnect-specific transport layer connection within a circuit that provides reliable port-to-port communication. In other words, VCs are the details of a circuit concerned with interconnect-specific reliable data delivery.

Circuits ensure the following:

• The delivery of messages without duplication or loss
• The sequential ordering of messages

The concepts of circuits and virtual circuits are so closely related that usually it has been unnecessary to differentiate between them because SHOW CLUSTER provides no view of the internal operation of a circuit. SCACP, however, makes the differentiation necessary by providing this internal view.

If cluster over IP is enabled, the virtual circuit can consist of both LAN and IP channels for cluster communications. Beginning with OpenVMS Version 7.3, SCACP has been used to manage and display information about the VCs underlying the circuits between LAN ports. Because SCACP displays different types of information about circuits and VCs, its commands must differentiate between them.

LAN cluster communications create virtual circuits using the NI-SCA Transport Protocol to communicate over LAN hardware, providing datagram services.

Cluster over IP create virtual circuits using the NI-SCA Transport Protocol to communicate over IP network using UDP protocol.

21.1.1.3 LAN Channels

A channel is a logical communication path between two LAN devices. Each channel between two nodes is determined by a local-remote pair of devices and the connecting network. For example, two nodes, each having two LAN devices, can establish up to four channels. The messages that a particular virtual circuit carries can be sent over any of the channels connecting the two nodes.

The LAN cluster driver, PEdriver, builds reliable virtual circuits using channels that the LAN adapters (devices) and the network connections define. It then uses these VCs to provide circuits to SCS.

21.1.1.4 IP Channels

Starting from OpenVMS Version 8.4, with the OpenVMS cluster over IP support, a channel is also a logical path between two IP interfaces. Each channel between two nodes is determined by a local-remote pair of devices and the connecting network. For example, two nodes, each having two LAN devices, can establish up to four channels. Similarly two nodes each having two IP interfaces (for example, IE0 and IE1 in Node A and WE0 and WE1 in node B) can establish up to four channels (IE0-WE0, IE0-WE1, IE1-WE0, IE1-WE1). The messages that a particular virtual circuit carries can be sent over any of the channels connecting the two nodes.

The IP cluster driver, PEdriver, builds reliable virtual circuits using channels that the IP interfaces and the network connections define. It then uses these VCs to provide circuits to SCS.

21.1.1.5 Channels and Virtual Circuits

The differences between channels and virtual circuits are the following:

• Channels are LAN or IP paths providing datagram service. In a LAN, the IEE 802.3 protocol is used and in IP based communication UDP (User datagram protocol) is used.
• NI-SCA port-to-port virtual circuits are layered on channels and provide error-free paths between nodes.

Multiple channels can exist between nodes in an OpenVMS Cluster system, but only one LAN/IP -based virtual circuit can exist between any two nodes at a time.

The following sections explain more recent functionality available for SCA circuits and ports and more recent support for SCS dynamic load class.

21.1.2.1 Ability to Set Port and Circuit Priorities

Beginning with OpenVMS Version 7.3-1, you have been able to exercise management control over the circuits chosen to be used for SCS connections. This control allows you to override the automatic selection of the circuit with the highest load class value.

To override automatic circuit selection, assign a management priority value to a specific circuit or SCA port. (A circuit's current priority value is the sum of the local port's management-assigned priority and the management priority value assigned to that circuit.)

Connections are assigned to a circuit with the highest priority. If multiple circuits have the highest priority value, then the circuit with the highest load class is selected.

A change in a circuit's current priority has one of the following effects:

• If a circuit's new current priority value is higher than another circuit's current priority, the connection is moved to the circuit with the higher current priority.
• Similarly, if a circuit's new current priority value is lower than another circuit's current priority, the connection moves to the circuit with the highest current priority.

You can use SCACP to enable or disable checksumming on a per-VC basis. For example, in a disaster-tolerant cluster, you might want to enable only checksumming on VCs to nodes at the remote site to ensure that failure of a LAN/IP device's checksumming function resulting in corrupted packets does not propagate to the remote site.

21.1.2.3 SCS Dynamic Load Class Support

Prior to OpenVMS Version 7.3-1, the load class of SCS circuits was determined only by the port's hard-coded load class value. As a result, CI or DSSI circuits were chosen over a Gigabit Ethernet circuit. Beginning with OpenVMS Version 7.3-1, PEdriver has dynamically updated the load class value of its SCS circuits to reflect the performance of the underlying LAN/IP path or paths currently in use.

If the circuits have the same priority, a change in a circuit's load class has one of the following effects:

• If a circuit's new load class value is higher than another circuit's current load class, the connection is moved to the higher load class circuit.
• Similarly, if a circuit's new load class value is lower than another circuit's load class, the connection moves to the circuit with the highest load class.

Beginning with V7.3-1, SCACP has provided the ability to display information about one cluster interconnect's local ports and their circuits with remote ports.

SCACP port and circuit data is intended to provide the information necessary to exercise management control over ports and circuits. SCACP is not intended to replace the copious data that SHOW CLUSTER provides for ports and circuits. The SHOW CLUSTER and SCACP utilities are intended to be used together to manage cluster communications.

SCACP port and circuit data show the following:

• SCACP port data shows an overview of a particular port's characteristics.
• SCACP circuit data shows the characteristics and the status of SCS communications with other nodes in the cluster.

You can also manage cluster communications by assigning a priority value to individual ports or circuits. See the SET CIRCUIT and SET PORT command descriptions.

21.1.4 Managing LAN/IP Cluster Ports

To manage LAN/IP cluster ports, you can use common port and circuit commands. Additional commands exist for LAN/IP port VCs, channels, and LAN devices on nodes in the cluster, IP interfaces in nodes in the cluster:

• VC data shows detailed internal information about the characteristics and operation of the NI-SCA transport layer connection underlying the circuit between the local and remote PEdriver ports.
• Channel data shows the characteristics of each LAN/IP communications path and shows how suitable each channel is for use by the virtual circuit.
• LAN device data shows low-level local LAN device characteristics, counters, and errors.
• IP interface data shows lower level IP interface characteristics, counters, and errors.

SCACP allows you to set channel and LAN/IP device priority. SCACP also allows you to start and stop PEdriver on LAN devices or IP interfaces.

Using the PEdriver Event-Tracing Facility

The LAN/IP cluster port driver, PEdriver, includes an event-tracing facility that collects a small amount of information for each defined event and saves it in a buffer associated with the virtual circuit or channel. (Any event not associated with a particular virtual circuit or channel is saved in a global PEdriver trace buffer.)

The event trace data is used when debugging, performing dump analysis, and looking at detailed aspects of PEdriver operation.

You can use SCACP to diagnose cluster communications problems. The appendix "Troubleshooting the NISCA Protocol" in HP OpenVMS Cluster Systems provides troubleshooting strategies to help cluster or network managers use SCACP and other tools to pinpoint network-related cluster communications problems.

21.1.6 Related Documents

For additional information on the topics covered in this chapter, see the following documents:

• HP OpenVMS Cluster Systems
• Guidelines for OpenVMS Cluster Configurations

The SCA Control Program (SCACP) is a cluster management utility that performs certain privileged cluster communications management functions.

Format

RUN SYS$SYSTEM:SCACP

To invoke SCACP, enter the following command at the DCL prompt:

$ RUN SYS$SYSTEM:SCACP

SCACP displays the following prompt, at which you can enter SCACP commands using the standard rules of DCL syntax:

SCACP> 

To exit SCACP and return to the DCL command level, enter the EXIT command at the SCACP> prompt or press Ctrl/Z.

SCACP also requires the following privileges:

• A minimum of DISPLAY privilege is required to enter commands that display information or influence SCACP execution (that is, SHOW, HELP, SPAWN, EXIT, and so on.)
• SYSPRV privilege is required to enter commands that change cluster communications operations (that is, SET, START, and STOP).

Example

$ CREATE COUNT.COM
SHOW LAN_DEVICE/COUNTERS
SPAWN WAIT 00:01:00
@COUNT
[Ctrl/Z]
$ RUN SYS$SYSTEM:SCACP
SCACP> @COUNT
      

This example creates and runs a command procedure, COUNT.COM, which displays device counters once a minute.

SCACP commands are provided for the following types of functions:

• Display
• Port selection
• Circuit selection
• Channel operation and selection
• LAN device/IP interface operation and selection
• Trace
• Miscellaneous: Help, Calculate, Spawn, Execute, and Exit

The SCACP commands are shown in Table 21-1.